Continuous grinding machine for machining a level workpiece surface

ABSTRACT

The subject matter of the invention is a continuous grinding machine for machining a level workpiece surface with at least two grinding tools ( 16 ) rotating about a vertical axis ( 24 ), each grinding tool ( 16 ) including a spindle ( 18 ) rotating about the vertical axis ( 24 ) and a disc grinder ( 20 ) mounted thereon, said at least two grinding tools ( 16 ) being disposed in one row across the feed direction of the workpiece ( 10, 12 ), and at least one disc grinder ( 20 ) being retained off center on the spindle ( 18 ) of concern.

This application claims Priority from German Application No. DE 20 2005 010 997.5 filed on 11. Jul. 2005

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a continuous grinding machine in accordance with the preamble of claim 1.

2. Description of the Prior Art

Continuous grinding machines for machining planar workpieces are preferably utilized for grinding the surface of plane pieces of furniture, all the more so when these furniture component parts are provided with milled out areas, profiles, rounded side edges or decorative strips. The surface is thereby deburred for example, the edges are milled or the surface ground for painting. Such type machines are also utilized for deburring metal parts and for polishing and cleaning surfaces. In order for the longitudinal, transversal or curved milled out areas, profiles or side edges to be sufficiently ground, the utilization of continuous grinding machines having disc-shaped grinding tools and/or grinding tools configured to be a rotating roll has proved efficient. Roll grinders are well suited for grinding milled out areas, profiles or edges that are substantially extending in the longitudinal direction of transport; milled out areas, profiles or side edges extending across the direction of transport however cannot be sufficiently machined by the roll grinders. Disc grinders rotating about a vertical axis so as to grind in any direction are utilized for this purpose. Whilst it is possible to design a roll grinder to cover the entire width of the workpiece, it is not economically sensible to utilize such large disc grinders. In practice, grinding stations having four, six or eight disc grinders arranged in a side-by-side relationship are utilized instead. If these disc grinders are disposed too close to each other, the centrifugal force will cause the grinding blades fastened thereon to hit and damage one another. As a result, the disc grinders must be spaced a certain distance apart. This in turn results in poor grinding of the workpiece in this portion for lack of a disc grinder.

To overcome this shortcoming, the U.S. Pat. No. 6,869,349 B2 proposes to cause the grinding station with the disc grinders mounted thereon to oscillate across the direction of transport of the workpieces. Such an oscillation device however is very costly on the one side and, on the other side, yields poor grinding results since the disc grinders do not really grind the portion being caused to oscillate and move since the relative speed of the disc grinders with respect to the workpiece surface in this portion may tend to zero.

It is also known from the U.S. Pat. No. 6,869,349 B2 to dispose to rows of disc grinders with the various disc grinders being staggered relative to each other. Although this makes it possible for the disc grinder to reach every portion of the workpiece surface, the various portions of the workpiece surface are not all ground with the same intensity so that the unsatisfactory grinding results are obtained. Moreover, the arrangement of two rows of disc grinding machines is very costly.

BRIEF SUMMARY OF THE INVENTION

In view thereof, it is the object of the present invention to provide a continuous grinding machine of the type mentioned herein above which machines the workpiece across its entire width using but a small number of disc grinders.

As a technical solution to this object, the invention proposes a continuous grinding machine in accordance with the features of claim 1. Advantageous developments of this continuous grinding machine will become apparent from the dependent claims.

A continuous grinding machine configured in accordance with this technical teaching has the advantage that, by mounting the disc grinder off center, said disc grinder is allowed to pass over a larger workpiece surface so that a relatively small disc grinder will pass over a relatively large workpiece surface. The advantage thereof is that, using the same number and size of disc grinders, the arrangement of the invention makes it possible to cover and, as a result thereof grind, a larger workpiece surface without quality deterioration. By mounting the disc grinder off center, the outer point of the disc grinder now passes over a circle of rotation the diameter of which corresponds to the distance of the fastening point from the outermost point of the disc grinder. The entire surface within the circle of rotation is covered and, as a result thereof, ground, by the disc grinder.

In a preferred embodiment, the distance between neighbouring vertical axes is smaller than the diameter of the circle of rotation of the disc grinder. The advantage thereof is that the circles of rotation of neighbouring grinding tools now overlap and that the two disc grinders machine the workpiece in the intersection. It has thereby been found advantageous to allow neighbouring grinding tools to rotate in the same direction of rotation since the intersection is then machined in opposite directions, which yields a very good grinding result.

Referring to prior art continuous grinding machines, the existing grinding tools can further be used in their existing spaced-apart relationship and the existing disc grinders as well; still, by mounting the disc grinder off center on the spindle, the circle of rotation of the disc grinder may be increased to an extent causing neighbouring circles of rotation to overlap and the workpiece to be machined across its entire width. This may allow the prior art oscillating transverse movement of the grinding tools to be eliminated. It has been found out that spacing the disc grinders about 0.5 cm to 5 cm, preferably 2 cm, from the center, will as a rule suffice to cover machining gaps.

In another preferred embodiment, neighbouring grinding tools are driven by means of a belt, a toothed belt more specifically. The advantage thereof is that one single electric motor will suffice to drive all the disc grinders so that the manufacturing cost needed can be reduced.

In another preferred embodiment, the disc grinder is configured to be ellipsoidal, rectangular or star-shaped so that the relief on the workpiece can be taken into account in order to achieve good grinding results.

In order to further improve the machining of the workpiece surface, it is proposed to mount a second row of grinding tool, with the grinding tools of the first row being staggered. This allows achieving that various grinding tools pass over each point of the workpiece surface so that a very good grinding result is obtained.

Further advantages of the continuous grinding machine of the invention will become apparent in the appended drawing and in the embodiments described herein after. Likewise, the invention lies in each and every novel feature or combination of features mentioned above or described herein after. The embodiments discussed herein are merely exemplary in nature and are not intended to limit the scope of the invention in any manner.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 shows a strongly schematized top view of a continuous grinding machine of the invention at a first stage;

FIG. 2 shows a strongly schematized top view of a continuous grinding machine of the invention at a second stage;

FIG. 3 shows a strongly schematized top view of a continuous grinding machine of the invention at a third stage;

FIG. 4 shows a front sectional view of two neighboring grinding tools in accordance with FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The FIGS. 1 through 3 illustrate in a strongly schematized view a continuous grinding machine on which a small workpiece 10 and a large workpiece 12 are transported in the direction of the arrow 14. Transverse to the direction of transport 14, four grinding tools 16 are disposed in one row, said tools each including a spindle 18 and a disc grinder 20, said disc grinder 20 being fastened off center on said spindle 18 and said spindle 18 and said disc grinder 20 rotating about a vertical axis 24 in the direction of the arrow 22. Since the disc grinder 20 is mounted off center on the spindle 18, the disc grinder 20 passes during one revolution over a circle of rotation 26 that is greater than the diameter of the disc grinder 20. The grinding tools 16 are disposed in such a manner that the distance between neighboring spindles 18 is smaller than the diameter of the circle of rotation 26 so that neighboring circles of rotation 26 overlap partially. In this intersection 28, every single one of the neighboring disc grinders 20 passes over the workpiece 10, 12, the disc grinders 20 passing over the intersection 28 in the opposite direction. As a result, the workpiece 10, 12 is ground across its entire width without gaps.

In the embodiment shown here, the disc grinder 20 of the grinding tools 16 are all mounted to the spindle 18 so as to be spaced the same distance apart therefrom. Moreover, the disc grinders 20 are all moved synchronously so that neighboring disc grinders 20 are prevented from colliding.

In another embodiment that has not been illustrated herein, another row of grinding tools is mounted in addition to the existing one so as to be staggered relative to the first row of grinding tools. This allows for even more uniform machining of the workpiece surface.

FIG. 4 illustrates two neighboring grinding tools 16 that are retained on a common carrier 30. Each grinding tool 16 includes a spindle 18 and a disc grinder 20 that is mounted off center on the spindle. The spindle 18 and the disc grinder 20 rotate about a vertical axis 24 and are driven by a common belt 32. The grinding tools 16 are connected to further grinding tools via additional belts that have not been illustrated herein so that only one grinding tool needs be driven through an electric motor in order to allow rotation of all the grinding tools.

Grinding blades 34, which are made from slotted abrasive cloth, are resting on the workpiece surface at their outer ends and machine the workpiece, are mounted coaxially with the vertical axis 24 on the disc grinder.

The height of the entire row of grinding tools 16 can be adjusted through the carrier 30 so that the grinding blades 34 only rest at their free end on the workpiece even if the workpieces differ in thickness.

On the commercially available continuous grinding machines, the distance between neighboring disc grinders is approximately 1 cm so that the workpiece is not machined in this area of about 1 cm. If the disc grinder 20 is now mounted 1 cm off its center on the spindle 18, this gap is closed both by the one disc grinder 20 and by the neighboring one so that each of the neighboring disc grinders passes over the workpiece in this area.

LIST OF NUMERALS

-   -   10 small workpiece     -   12 large workpiece     -   14 direction of transport/arrow     -   16 grinding tool     -   18 spindle     -   disc grinder     -   22 arrow     -   24 vertical axis     -   26 circle of rotation     -   28 intersection     -   30 carrier     -   32 belt 

1. A continuous grinding machine for machining a level workpiece surface with at least two grinding tools (16) rotating about a vertical axis (24), each grinding tool (16) including a spindle (18) rotating about the vertical axis (24) and a disc grinder (20) mounted thereon, and said at least two grinding tools (16) being disposed in one row across the feed direction of the workpiece (10, 12), characterized in that at least one disc grinder (20) is retained off center on the spindle (18) of concern.
 2. The continuous grinding machine as set forth in claim 1, characterized in that the distance between neighboring vertical axes (24) is smaller than the diameter of the circle of rotation (26) of the disc grinder (20).
 3. The continuous grinding machine as set forth in claim 1, characterized in that neighboring disc grinders (20) are retained at the same distance from the center on their spindles (18) so that the grinding tools (16) rotate off center at the same pace.
 4. The continuous grinding machine as set forth in claim 1, characterized in that neighboring grinding tools (16) rotate in the same direction of rotation.
 5. The continuous grinding machine as set forth in claim 1, characterized in that the disc grinder (20) is mounted about 0.5 cm to 5 cm, preferably between 1 cm and 2 cm, off center on the spindle (18).
 6. The continuous grinding machine as set forth in claim 1, characterized in that neighboring grinding tools (16) are joined together by means of a belt (32), a toothed belt more specifically.
 7. The continuous grinding machine as set forth in claim 1, characterized in that the disc grinder is configured to be ellipsoidal, rectangular or star-shaped.
 8. The continuous grinding machine as set forth in claim 1, characterized by a second row of grinding tools, the grinding tools of the second row being offset with respect to the grinding tools of the first row in such a manner that the grinding tools are staggered. 